Beaton, Alec A., Alexandria Guinness, and John M. Franck. “A Robust, Modern Strategy for Treating Coherence Pathways in Unstable and Inhomogeneous Magnetic Resonance Experiments.” ArXiv:2202.03313 [Physics], February 7, 2022.
http://arxiv.org/abs/2202.03313.
Over recent decades, motivated either by practicality or the need to tap into new types of measurements, the science of Magnetic Resonance has expanded into more adverse conditions: deliberately chosen lower frequencies, inhomogeneous fields, and/or time-variable fields. In particular, Overhauser Dynamic Nuclear Polarization (ODNP) presents a case study that challenges previous expectations and offers an interesting test-bed for further developments. For example, an interest in the nanoscale heterogeneities of hydration dynamics demand increasingly sophisticated and automated measurements deploying ODNP on a modular, open source instrument operating at 15 MHz. ODNP demands the acquisition and automated processing of large quantities of one dimensional NMR spectra, which can present various problems: in particular, unambiguous identification of signal in newly configured instruments presents a practical challenge, while field drift tends to remain an issue even in fully configured instruments. Recent advances in the capabilities of open-source libraries opened up the opportunity to address these issues at the fundamental level, by developing a specific schema that treats the phase cycle of a pulse as an explicit “phase domain” dimension that Fourier transforms into the “coherence domain.” In particular, a standardized protocol for organizing and visualizing the resulting data clearly presents all the information available from all coherence transfer pathways of a phase-cycled experiment, with intelligible results that don’t rely on preliminary phase corrections. It thus organizes and visualizes data in ways that more accurately reflect the rich physics of the underlying NMR experiments, and that more fully bear out the original fundamental concepts of coherence transfer pathways.